After identifying a nonlinear ARX model, you can use the model for the following tasks:
Simulation and prediction —
At the command line, use
predict to simulate and predict the model
output. To compare models to measured output and to each other, use
compare. For information about plotting
simulated and predicted output in the app, see Simulation and Prediction in the App.
You can also specify the initial conditions for simulation and prediction.
The toolbox provides several options to facilitate how you specify
initial states. For example, you can use
data2state to compute state values based
on the requirement to maximize fit to measured output or based on
operating conditions. See the
page for a definition of the nonlinear ARX model states. To learn
more about how
the model output, see How the Software Computes Nonlinear ARX Model Output.
You can also forecast the response of a dynamic system by using
forecast command. The command
predicts future outputs of the system using past output measurements.
For more information, see Forecasting Response of Nonlinear ARX Models.
linearize command provides a first-order
Taylor series approximation of the system about an operating point.
a linear approximation of a nonlinear model for a given input data.
For more information, see the Linear Approximation of Nonlinear Black-Box Models. You can compute the
operating point for linearization using
After computing a linear approximation of a nonlinear model, you can perform linear analysis and control design on your model using Control System Toolbox™ commands. For more information, see Using Identified Models for Control Design Applications and Create and Plot Identified Models Using Control System Toolbox Software.
Simulation and code generation
using Simulink® — You can import estimated nonlinear
ARX models into the Simulink software using the Nonlinear ARX
block (IDNLARX Model) from the System
Identification Toolbox block library. Import the
idnlarx object from the workspace into Simulink using
this block to simulate the model output.
The IDNLARX Model block supports code generation
Coder™ software, using both generic and embedded
targets. Code generation does not work when the model contains
estimator, or custom regressors. For more information, see Simulate Identified Model in Simulink.